Apparatus for centrifugal casting of tubular objects

ABSTRACT

In a conventional de Levaud centrifugal pipe casting machine which includes a rotatable water casing, a mold within the casing and rotatable therewith, cooling water supply and discharge system, ball bearings rotatably supporting the water casing, sealing glands, and means through which rotation of the water casing is effected, the improvement comprising casing sleeves mounted exteriorly at each end of the water casing which support casting machine parts such as cooling water supply and discharge system, ball bearings, sealing glands, etc., and are detachably secured to the water casing for rotation. When it is desired to remove the water casing from the casting machine, the casing sleeves are detached and moved apart to present the water casing free of the auxiliary machine parts.

United States Patent Wahlet al.

[451 Mar. 28, 1972 [54] APPARATUS FOR CENTRIFUGAL CASTING OF TUBULAROBJECTS Luitpoldhutte Aktiengesellschaft, Amberg, Germany [22] Filed:Mar.21,1969

[21] App]. No.: 826,039

[73] Assignee:

[30 l' oreign Application Priority Data Mar. 22, 1968 Germany ..P 17 58026.6

[52] US. Cl ..l64/29l, 164/297, 164/298 [51] Int. Cl ..B22d 13/10 [58]Field oiSearch ..l64/84,114,115,l16,117, 164/118, 175, 286, 287, 288,291, 292, 293, 294,

2,252,219 8/1941 Trotzke ..164/291 2,461,765 2/1949 Olt ..l64/l 14 X2,500,799 3/1950 Carrington.. ..164/291 2,681,485 6/1954 Smith ..l64/114X FOREIGN PATENTS OR APPLICATIONS 995,992 12/1951 France 164/297 GermanyGreat Britain 164/1 14 Primary Examiner--Robert D. Baldwin AssistantExaminer-John E. Roethel Attorney-Hammond & Littell [57] ABSTRACT In aconventional de Levaud centrifugal pipe casting machine which includes arotatable water casing, a mold within the casing and rotatabletherewith, cooling water supply and discharge system, ball bearingsrotatably supporting the water casing, sealing glands, and means throughwhich rotation of the water casing is effected, the improvementcomprising casing sleeves mounted exteriorly at each end of the watercasing which support casting machine parts such as cooling water supplyand discharge system, ball bearings, sealing glands, etc., and aredetachably secured to the water casing for rotation. When it is desiredto remove the water casing from the casting machine, the casing sleevesare detached and moved apart to present the water casing free of theauxiliary machine parts.

4 Claims, 5 Drawing Figures PATENTED MR 2 8 I972 SHEU 1 UF 3 ATTORNE SPATENEnmzs m2 SHEET 3 BF 3 3 Q3 3 xv ATTORNEYS APPARATUS FOR CENTRIFUGALCASTING OF TUBULAR OBJECTS PRIOR ART The de Levaud process of castingpipe in permanent metal molds has been extensively practiced for manyyears. Present processes, in which the metal temperature is particularlycritical and must be maintained within a very narrow range, comprise theuse of cylindrical metal molds disposed within a water jacket andadapted to be rotated at suitable speeds. Rollers are mountedcircumferentially of the water jacket at spaced intervals thereof tofacilitate rotation. The water jacket is mounted on wheels so that theentire assembly can be moved by means of a hydraulic cylinder in thedirection of the longitudinal axis of the mold. This movement is along afixed bed inclined slightly from the horizontal. The molten metal is fedinto the mold through a similarly inclined trough which is mounted atthe upper end of the fixed bed and extends like a cantilever beam almostthe full length of the mold when the mold is at the extreme upperposition. When the mold is in this position, it is ready for casting.After the casting machine ladle has been filled, the machine operatorbrings the mold up to speed and actuates the mechanism controlling thetilting of the ladle. In a few seconds, the iron has filled the bellspace, at which time, the operator starts the mold carriagelongitudinally down the inclined bed. The stream of iron discharged fromthe trough is distributed along the surface of the mold where it is heldin place by centrifugal force and forms the pipe upon cooling. After themetal has solidified, mold rotation is stopped and the pipe is extractedfrom the mold by moving mold carriage longitudinally up the inclined bedwhile holding the pipe stationary. The mold carriage is then moved backdown the inclined bed to place the mold in a convenient position forsetting the bell core, and if a mold coating is used, it may be appliedduring this stroke of the machine. The bell core is then set and themold carriage moved to the extreme upper end of the inclined bed tobegin another casting cycle.

The distribution of the metal along the mold length during the castingoperation is controlled by the operator who must commence movement ofthe mold assembly away from the trough at the correct moment or else themetal delivered to the bell end will not give the proper bell endthickness. For instance, if the carriage movement is started to soon thebell end will be too thin, and if it started late the bell end will bethick. Since it is usually impractical to place the machine operator ina position which commands a good view of the bell end of the mold, it isusually necessary to have a bell core setter, who is in a position whichaffords the best view of the bell end of the mold, signal the operatorto start the mold carriage retraction away from the trough. This iscalled flagging and is accomplished by throwing a switch which turns ona light or other suitable signal on the operators panel.

In addition to starting the mold retraction at the proper instant, theoperator must also judge the proper position in which to stop the moldcarriage momentarily while the spigot end of the pipe is being cast,following which, retraction of the mold carriage is completed and theladle pouring is terminated. This is known as hand-checking and isnecessary to build up the proper metal thickness at the spigot end ofthe mold. It is apparent that it is completely within the control of theoperator who determines both the position and the duration of the stop.When the mold movement is stopped in the wrong position or for too shorta time, the spigot end is made thin, and if it is stopped for too long atime, the spigot end is cast thick.

Semi-automatic controls to control flagging, hand-checking and ladlecut-back have been provided on the centrifugal pipe casting machinesreplacing human judgement and thereby obtaining a pipe of more uniformthickness.

In the course of development in the art of centrifugal casting machines,it was customary to support the water casing by means of at least twogroups of two to three rollers distributed along a partial circumferenceof the water casing. The rotation of the water casing in such anarrangement was strained and non-uniform resulting in accelerated wearof rollers. Additional means was generally provided in the form ofcounterrollers to bufi'er axial forces. Needless to say, unsteadyrotation of the water casing, and the mold within, unfavorablyinfluenced the quality of pipes produced thereby.

To improve the situation, it was proposed to use ball bearings forrotatably supporting the water casing. These ball hearings were arrangedaround the full circumference of the water casing and indeed provided asmoother and much more efficient rotation in terms of the higher qualityof pipe produced.

Although the ball bearings, arranged as described above, did resolve oneproblem, they spawned a number of new ones. When it was desired toremove the water casing from the casting machine, the ball bearings hadto be removed which required a considerable amount of time and resultedin long periods of idleness of the casting machine. Multiplying thistime by the number of casting machines in the plant gives an indicationof amount of time that was unnecessarily wasted. Furthermore, when thewater casing was removed from a casting machine, it was necessary tohave an extra set of ball bearings on hand for another water casingwhich was to be installed in the casting machine. The necessity forproviding additional set of ball bearings every time a different watercasing was installed increased investment costs which directly affectedthe cost of the pipes produced. It should be now apparent to one that,in addition to the multitudinous overhead and production costs, the costof the pipes was further inflated by the cost of replacement sets ofball bearings and by inefficient utilization of the casting machines.

OBJECTS OF THE INVENTION It is an object of this invention to obviatedisadvantages of the prior art centrifugal casting machines by reducingmachine shut-down time and investment cost.

It is another object of this invention to provide a centrifugal metalcasting machine whereby the time for changing water casing, togetherwith the mold is substantially reduced.

It is still another object of this invention to provide a centrifugalmetal pipe casting machine which incorporates a design feature allowingfor thermal expansion and contraction.

A further object of this invention is to provide a pipe casting machinewhich would allow for remaining the auxiliary parts mounted on thecasing sleeves while replacing the water casing.

THE INVENTION The present invention relates to a centrifugal pipecasting machine which comprises a water casing and an integral molddisposed therein, rotatably mounted on carriage provided with wheels andserving as a conveying means for the mold assembly. Rotary movement tothe water casing and the mold may be imparted by an electric motormounted on the frame of the machine and operatively connected to thewater casing through suitable gearing or belt-drive and through casingsleeves exteriorly mounted at the extremities of the water casing. Thewheels of the carriage are arranged to travel on rails fixed to aninclined base of the casting apparatus. A piston operating in a cylindersecured to the base has its outer end connected to the carriage formoving the carriage to and from on the rails during the castingoperation.

A pouring trough, of a well-known type is fixed at its inlet by means ofsupport which is rigidly mounted with respect to the base so that theoutlet end may move in and out of the mold as the mold carriage is movedback and forth on its tracks. Molten metal is supplied to the pouringtrough through a spout curving downwardly from the outlet of a ladle.Titlting of the ladle is effected by means of a piston-cylinderarrangement about trunnions affixed to the ladle.

The novel aspect of this invention resides in the provision of asupporting casing sleeve on the end portions of the water casing. Thecasing sleeves are detachably secured to the water casing and rotatetherewith during the casting operations. Auxiliary parts of the castingmachine, such as cooling water supply and discharge system, ballbearings, sealing glands and various other attachments which arenonnally mounted on the water casing are, in accordance with the presentinvention, mounted on the casing sleeves. Each casing sleeve isrotatably secured to and supported by a separate sled which is attachedto an intermediate carriage platform of a carriage by means of a pistonreciprocating in a double-acting cylinder. This piston is rigidlysecured to the sled and slidably communicates with the double-actingcylinder disposed within the intermediate carriage platform. When it isdesired to replace the water casing, a support means is provided for thewater casing. The water casing is detached from the casing sleeves atboth ends thereof and the pistons are actuated to disengage the casingsleeves from the water casing, leaving a detached water casing restingon the support means. The water casing can subsequently be removed toany desired location by means of a crane.

In the accompanying drawings, which illustrate the preferred embodimentof the invention,

FIG. 1. is a cross-sectional view of the water casing.

FIG. 2. is a cross sectional view of the pair of easing sleeves.

FIG. 3. is a cross-sectional view through the bell end of thecentrifugal pipe casting machine.

FIG. 4. is a cross-sectional view through the spigot end of the pipecasting machine.

FIG. 5. is a view of the sled taken through plane of FIG. 3.

Referring to the drawings, the water casing 10, separately illustratedin FIG. 1, has a plurality of circumferentially arranged lugs l2, 14 onits periphery. As shown in FIGS. 3 and 4, mold 20 is positioned withinwater casing and is spaced therefrom by adjustable spacers 22 whichproject from the water casing into the cooling water chamber. The moldillustrated in the drawings is integral at its end with the watercasing, as is apparent from FIG. 3.

The casing sleeves 16, 18 are journaled over the end portions of watercasing 10, and are secured thereto by means of bolts 24 projectingthrough lugs l2, l4 and into bores 26, 28 provided in the bell end andspigot end of the casing sleeves, respectively. Cooling water supply anddischarge assembly, generally designated by numeral 30, is supported bythe respective casing sleeves and is in communication with by the watercasing 10 through conduit 34. Rotation of the water casing 10, togetherwith the casing sleeves l6, 18, is facilitated by ball bearings 36mounted around the circumference of the casing sleeves and disposed insupporting relationship. O-rings 38 and sealing glands 40 provide' forsealing between cooperating parts. Rotation of the water casing, casingsleeves and the mold is effected by an electric motor suitably mountedon the frame of the casting machine through what may be a V- beltoperatively engaging a drive-gear 42 on the casing sleeve 16. Rotationof the mold assembly may also be effected by any other suitable means,such as cooperating set of gears.

The mold assembly is supported at each end on carriage 44 by structuralelements forming chamber 46 and cylindrical support block 48. As isevident from FIGS. 3 and 4, the cylindrical support block 48 also formsa supporting surface for ball bearings 36. Carriage 44 consists of sleds50, 52 and an intermediate carriage flatform 54. Sled 52 is detachablysecured to the intermediate carriage platform 54 by a pair ofcooperating lugs 56, 58 situated on the sled and the intermediatecarriage platform, slotted bolt 60, and wedge 62 driven into the slot.

Interaction between the intermediate carriage platform 54 and the sledsis further enhanced by a stem 64 which extends longitudinally from eachsled, and a piston 66 attached to the stern and disposed forreciprocating movement in a doubleacting cylinder 68 provided at eachend of the intermediate carriage platform 54.

Each piston 66 can be independently acuated, in a manner well known inthe art, to impart relative movement between each sled and theintermediate carriage platform 54. A plurality of swingable supports 70are disposed on the carriage 44 along the extent of the water casing toprovide additional support thereto. These supports are swung outwhenever it is desired to remove the water casing. The carriage issupported on wheels 72, 74 which ride on tracks disposed on an inclinedsurface.

In operative relationship, sled 50, is firmly linked with theintermediate carriage platform 54 by aligned lugs 56, 58, bolt 60 andwedge 62 driven into the slot in said bolt 60. Sled 52 can be shiftedrelatively to the platform 54 for compensation of thermal expansions andcontractions. Supports 70 are swung to their operative position andmaintain water casing in the horizontical plane, relative to theinclination of the machine bed. The mold assembly is rotated by a V-beltdriven by an electric motor and engaged to the mold assembly throughdrive-gear 42. Casing sleeves l6, 18 are rigidly secured to water casing10 by bolts 24 and rotate therewith in unison.

Due to special design features of the casting apparatus described above,expansion and contraction of the machine parts due to thermal cycle ofthe centrifugal casting process are easily compensated thereby. Thisfeature of the apparatus is shown in the drawings as exteriorfrusto-conical surfaces 76, 78 on water casing 10 and mating interiorsurfaces 80, 82 on respective casing sleeves l6, 18. When axial thermalexpansions and contractions are induced, they are compensated byrelative movement of sled 52.

When it is desired to replace water casing 10 together with mold 20, thecasing sleeves 16, 18 are disconnected from water casing 10 byextracting bolts 24, and sled 50, is disconnected from intermediatecarriage portion 54 by removing wedge 62 and bolt 60. A crane is movedover the water casing and cables are draped around the water casing.Supports 70 are swung out from under the water casing and thedouble-acting cylinders 68 are actuated to cause movement of the sledsaway from the intermediate carriage platform 54. Since the casingsleeves 16, 18 are rotatably secured to respective sleds '50, 52,outward movement of the sleds will eventually clear casing sleeves 16,18 from water casing 10, leaving the water casing suspended by the cranecables. Thereafter, the water casing is moved by crane to any desiredlocation. To re-assemble the casing apparatus, another water casing isinstalled by positioning it between the casing sleeves, actuating thedouble-acting cylinders to move the sleds inwardly until the watercasing is snugly nestled within opposing casing sleeves. The reassemblyprocedure is completed by securely fastening the casing sleeves to thewater casing, and the sleds to the intermediate carriage platform.

Various modifications of the centrifugal pipe casting apparatusdescribed herein may be made without departing from the spirit of scopethereof. It is to be understood that their invention is to be limitedonly as defined by the appended claims.

We claim:

1. A centrifugal pipe casting apparatus comprising a water casingprovided with casing sleeves journaled on its ends mounted for rotation,a mold disposed in said water casing in spaced relationship androtatable therewith in unison, means for detachably securing said casingsleeves to the water casing for rotation, auxiliary casting partsmounted on said casing sleeves, moveable support means for said sleevescomprised of an intermediate carriage platform and a detachable sled oneach end of said platform, means for rotatably affixing said sleeves tosaid sleds and means for imparting relative movement between each sledand the intermediate carriage platform whereby the casing and mold canbe separated from the rest of the apparatus without disassembly thereof.

2. The apparatus of claim 1 wherein the means for imparting relativemovement between the sleds and the intermediate carriage platform is adouble-acting piston cylinder arrangement.

6 3. The apparatus of claim 2 wherein a piston is attached to 4. Theapparatus of claim 1 wherein each end of the water each of said sledsand a cylinder is disposed at each end of said casing 11 u mfial xt riorurface and each casing platform whereby a piston of one sled isoperatively disposed Sleeve has 3 mating ifltel'ior surface assure axialalignment is one of said cylinders and the other piston is operativelyofthe Sleeves and casmg' disposed in the second cylinder.

1. A centrifugal pipe casting apparatus comprising a water casingprovided with casing sleeves journaled on its ends mounted for rotation,a mold disposed in said water casing in spaced relationship androtatable therewith in unison, means for detachably securing said casingsleeves to the water casing for rotation, auxiliary casting partsmounted on said casing sleeves, moveable support means for said sleevescomprised of an intermediate carriage platform and a detachable sled oneach end of said platform, means for rotatably affixing said sleeves tosaid sleds and means for imparting relative movement between each sledand the intermediate carriage platform whereby the casing and mold canbe separated from the rest of the apparatus without disassembly thereof.2. The apparatus of claim 1 wherein the means for imparting relativemovement between the sleds and the intermediate carriage platform is adouble-acting piston cylinder arrangement.
 3. The apparatus of claim 2wherein a piston is attached to each of said sleds and a cylinder isdisposed at each end of said platform whereby a piston of one sled isoperatively disposed is one of said cylinders and the other piston isoperatively disposed in the second cylinder.
 4. The apparatus of claim 1wherein each end of the water casing has a frusto-conical exteriorsurface and each casing sleeve has a mating interior surface to assureaxial alignment of the sleeves and casing.